Drilling unit for rotary drilling of wells

ABSTRACT

A drilling unit for rotary drilling of wells using casing as the drill string. The drilling unit is a self-contained assembly designed to be bodily inserted and withdrawn through the bore of a well casing string and comprises releasable latch means for non-rotatively locking the structure to the casing; a rotary power unit supported by the latch means and rotatively connected to a bit assembly. The latter comprises a main or pilot bit and a plurality of radially extendible and retractable underreamers actuated by fluid pressure which may first be employed for driving the power unit.

United States Patent Brown 1 May9, 1972 [54] DRILLING UNIT FOR ROTARYDRILLING OF WELLS [72] Inventor: Cicero C. Brown, 5429 Sturbridge Dr.,

Houston, Tex. 77027 [22] Filed: May2l,1970

[21] App1.No.: 39,226

1,841,302 1/1932 Simmons ..175/106 X 3 ,097,707 7/1963 Kammerer3,545,553 12/1970 Kammerer 3,507,329 4/1970 Stone ..l66/217 X 2,997,1198/1961 Goodwin ..l75/267 X Primary Examiner-Robert L. Wolfe Attorney-R.Werlin 5 7 ABSTRACT A drilling unit for rotary drilling of wells usingcasing as the drill string. The drilling unit is a self-containedassembly designed to be bodily inserted and withdrawn through the boreof a well casing string and comprises releasable latch means fornon-rotatively locking the structure to the casing; a rotary power unitsupported by the latch means and rotatively connected to a bit assembly.The latter comprises a main or pilot bit and a plurality of radiallyextendible and retractable underreamers actuated by fluid pressure whichmay first be employed for driving the power unit.

6 Claims, 11 Drawing Figures [52] US. Cl ..I75/I07,166/217,175/104,175/258 [51] Int-CI ..E2lb3/l2 {58] Field of Search ..l75/257, 258, 276,286, 261, 175/263, 107, 104, 97; 166/217 [56] References Cited 7 UNITEDSTATES PATENTS 2,898,087 8/1959 Clark ..175/258 X 2,719,700 10/1955Kammerer "175/271 3,130,788 4/1964 Cochran ..166/217 2,663,546 12/1953Kammerer ..l75/276 PATENTEDMM 91972 sum 3 OF 4 $22.4 i i i c/cERo a,Beam/N [4 VI; I018.

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A TTOE/VE) DRILLING UNIT FOR ROTARY DRILLING OF WELLS Rotary drilling ofwells is commonly performed using a string of relatively small diameterdrill pipe by which a larger diameter bit is rotated to drill a borehole of the desired diameter. Casing to fit the large diameter bore holeis then inserted in the bore hole to line and support the wall thereof.Drilling in the uncased bore hole and the multiple operations involvedin running separate drilling and casing strings necessarily increase thecost of the well and is subject to hazards of various types well knownin the drilling industry.

Various systems have been proposed for drilling using the casing stringas the drill pipe and such systems are disclosed in certain of myearlier copending applications, to wit: Ser. No. 778,509, filed Nov. 25,1968 now U.S. Pat No. 3,552,507; Ser No. 803,9l l, filed Mar. 3, 1969now U.S. Pat. No. 3,552,508; and Ser. No. 857,046, filed Sept. ll, 1969now U.S. Pat. No. 3,552,509. These systems employ separate bitassemblies, which are designed to be bodily inserted and removed throughthe casing and locked to the lower end thereof for rotation by thecasing. Such bit assemblies include combinations of main or pilot bitwith a plurality of radially extensible and retractable underreamers.

As noted, the earlier systems contemplate arrangements in which thecasing string itself is rotated to drive the bit section. This requiresa rotary power apparatus at the surface to rotate or drive the casingstring, and while such systems are found to be practical and reasonablysuccessful, some problems occur which it is desirable to avoid to makethe system even more successful from a practical standpoint. Theprincipal problems include those arising form the need to provide aneffective power apparatus for rotating the relatively large diametercasing particularly when the string has reached an extended length asthe bore hole attains continuously increased depth.

The present invention contemplates an improved system which employs theseparate form of drilling unit which is bodily inserted and withdrawnthrough the casing string, as in the earlier applications, but whichincludes as a part thereof a rotary power unit for driving the bitsection while the casing string remains stationary and is merely fedinto the bore hole behind the bit as the hole deepens. The power unitmay be any of several known types of hydraulic motor or turbine units or'may be an electrically powered motor of known design.

More specifically, the illustrative embodiment of the present inventioncontemplates a drilling unit which comprises an anchor or latch elementfor releasably securing the unit to the lower end of the casing; a bitsection comprising a main or pilot bit and a set of radially extendibleand retractable underreamers; and a rotary power drive member connectingthe anchor element to the bit. The rotary drive member is in the form ofa hydraulic motor which is driven by pressure fluid, such as drillingmud pumped down through the casing. The underreamers are pivotallymounted to the body of the bit section and connected to an actuatingplunger which is spring biased to urge the underreamers to theirextended positions. The underreamers are initially secured in reactedposition by shear pins or the like which are breakable by fluid pressureapplied to the plunger, the pressure fluid being the same as thatemployed to drive the power unit.

By the described system a well bore can be drilled to a desired depthwhile the hole is being continuously lined with casing without requiringrotation of the latter. The drilling unit can be inserted into andremoved through the bore of the casing as required at any time duringthe drilling procedure.

Other and more specific objects and advantages of this invention willbecome more readily apparent from the following detailed descriptionwhen read in conjunction with the accompanying drawing which illustratesa useful embodiment in accordance with this invention.

In the drawing:

FIGS. 1A and 1B, together, comprise a longitudinal sectional view of thedrilling tool inserted in the casing string on a running stringimmediately prior to being locked to the casing; the underreamers of thebit section being shown in their retracted positions;

FIGS. 2A and 23, together, comprise a view similar to FIGS. 1A and 18showing the anchor element locked to the casing and the underreamers intheir extended relation;

FIG. 3 is a view similar to FIGS. 1A and 2A, showing the running tool inprocess of being released from the anchor element;

FIG. 4 is a partial view of the tool portion illustrated in FIG. 3showing a fishing tool in engagement with the anchor element preparatoryto effecting release thereof to permit withdrawal of the drilling unitfrom the casing;

FIGS. 5 and 6 are cross-sectional views taken respectively on lines 5-5and 6-6 of FIG. 1A;

FIG. 7 is a cross-sectional view taken in line 7-7 of FIG. 2B; and, Y

FIGS. 8A and 8B, together, comprise a longitudinal sectional view of'thehydraulic power unit employed for rotating the bit section.

Referring to the drawing, there is shown the lower end of a string ofpipe P, conventionally referred to as casing, to which is threadedlyconnected a landing shoe 10 having a bore 11 matching the bore of thecasing, and flared at its lower end 12. A plurality of angularly spacedsplines or landing pins 13 project into bore 11 and an annular latchingor anchor recess 14 is provided in the wall of bore 11 a short distanceabove landing pins 13.

The drilling unit, designated generally by the letter U comprises ananchor sub-assembly A, a power drive assembly B connected to the anchorsub-assembly, and a bit section C connected to drive assembly B forrotation thereby. The overall dimensions of the drilling unit as a wholeare made such that the unit may be bodily inserted and withdrawn throughthe bore of casing P.

anchor sub-assembly A includes a tubular body 16 having an axial bore 18and terminating at its lower end in an externally threaded pin 20 bywhich it is connected to the housing 22 of the power drive assembly B.The upper end portion of body 16 is enlarged in internal diameter todefine the enlarged bore 24 enclosed by a tubular cage 26. The latterhas a plurality of angularly spaced, rectangularly shaped, radialopenings 28 in which correspondingly shaped anchor .dogs 30 are mountedfor radial movement into and out of anchoring engagement with recess 14.The extension of body 16 is provided with a plurality of angularlyspaced, longitudinally extending spline slots 32 open at their lowerends to receive landing pins 13 and closed at their upper ends to formlanding shoulders 34 to be engaged by pins 13 for landing the drillingunit in the landing shoe 10' and forming a non-rotative connectionbetween the anchor sub-assembly and the landing shoe. The spacingbetween shoulders 34 and openings 28 is made such that when the anchorassembly is landed on pins 13, dogs 30 will be in registration withrecess 14. An annular seal element 36 is circumferentially mounted inthe exterior of body 16 between shoulders 34 and openings 28 to seal offbore 11 below anchor recess 14. The upper end of cage 26 is connected toa running collar 38 which has an annular seal 40 circumferentiallymounted in the exterior thereof to seal off bore 11 above recess 14.

The anchor sub-assembly includes a tubular setting sleeve 42 mounted foraxial sliding movement in bore 24 of the anchor cage. Sleeve 42 carriesan annular external enlargement 44 intermediate its ends adapted toproject anchor dogs 30 radially outwardly into anchoring engagement inrecess 14 when the sleeve is moved downwardly sufficiently to moveenlargement 44 behind the dogs (FIGJA) and to release the dogs forretraction from recess 14 when the sleeve is subsequently moved upwardlyto raise enlargement 44 above the dogs (FIG. 1A).

The external diameter of the portion of setting sleeve 42 aboveenlargement 44 is made sufficiently less than the internal diameter ofcollar 38 to provide an annular space 46 of sufficient width to receivetherebetween a shear sleeve 48. Setting sleeve 42 is initially securedin its upper inactive position with respect to dogs 30 by one or moreshear screws 50 which extend transversely through collar 38, shearsleeve 48 and into setting sleeve 42. When thus shear-pinned together,the lower end of shear sleeve 48 rests on the upper end of cage 26. Theupper end of shear sleeve 48 is provided with an inwardly extending lip52 adapted to overhang an external shoulder 54 on the running collar 56carried by the lower end of a conventional running tool string S, thedetails of which do not form a part of this invention.

Power drive unit B may be of any suitable and known form capable ofrotating the bit section, the details of which do not form a part ofthis invention. However, for purposes of this description, there isillustrated in FIGS. 7A and 78, more or less diagrammatically, a form ofpower unit, commercially known as a Dyna-Drill," manufactured byDyna-Drill Company of Long Beach, California, which is essentially ahydraulic motor of the Mayno screw type, comprising a single threadrotor 60 running in a rubber lined spiral passageway 61 and adapted tobe rotated by hydraulic fluid pumped down through casing P. Rotor 60 issuitably connected to a drive shaft 62 the lower end of which carries athreaded pin 63 by which the drive shaft is operatively connected to thebit section C by means of a tubular coupling 64 having a threaded box 65at its upper end for receiving pin 63 and an externally threaded pin 66at its lower end.

Bit section C includes a tubular body 70 having a bore 71 and aninternally threaded box 69 at its upper end for receiving coupling pin66. The lower end of body 70 carries a tubular collar 72 having an axialbore 73 and terminating in an internally threaded box 74 adapted toreceive the hollow shank 75 of a conventional bit 76 which may be aroller-type bit as shown or may be a drag-type or other known form ofbit adapted to serve as the main or pilot bit in boring the drill hole.

' The wall of body 70 above collar 72 is provided with a plurality ofangularly spaced, longitudinal slots 68 in each of which is pivotallymounted an underreamer, designated generally by the letter R.

An annular piston 77 is slidably reciprocable in bore 71 above slots 68and forms the head of a downwardly extending tubular plunger 78 having abore 79 which opens through the center of piston 77. The lower end ofplunger 78 extends slidably through the central opening 80 of a conicalcap 81 closing the upper end of bore 73 of collar 72. Plunger 78 isresiliently biased downwardly by a strong coil spring 82 mounted incompression between piston 77 and the inner end of coupling 64.

Each of the underreamers R comprises a cutter arm 83 and a crank arm 84extending at an angle to the cutter arm. A pivot pin 85 extendstransversely through the crank arrn adjacent its juncture with thecutter arm and is journaled in the walls of slot 68 (FIG. 7). The freeend of the cutter arm carries an inwardly extending cutter shaft 86 onwhich is rotatably mounted a frustoconical cutter 87 of a generallyconventional design. Crank arm 84 is formed with an extension 88, thefree end of which carries an inwardly projecting crosshead pin 89positioned in a crosshead slot 90 provided in a related side portion ofplunger 78 (FIG. 7). With this arrangement, it will be seen thatmovement of plunger 78 downwardly will act on crosshead pins 89 andthence through extensions 88 and crank arms 84 to rotate theunderreamers outwardly while reverse movement of the plunger will act toretract the underreamers. Since coil spring 82 normally tends to urgeplunger 78 downwardly and thereby bias the underreamers to theirextended positions, the underreamers are initially secured in theretracted position (FIG. 18) by means of shear pins 91 which extendtransversely through the cutter arm into the walls of the related slots68. Breaking of shear pins 91, as will be described hereinafter, willrelease the underreamers for movement to their extended positions.

A plurality of jets 92 are mounted in the walls of cap 81 and directedso as to discharge fluid upwardly and outwardly at an angle selected tocause the fluid to strike the teeth of the extended cutters 87 to washcuttings therefrom, as well as to impinge on the wall of the well boreat points immediately in advance of the cutters to apply a softening orerosive action thereon which will improve the cutting efficiency of theunderreamers.

In operation, drilling unit U will be suspended from running string S bythe connection between running collar 56 and shear sleeve 48, all of theseveral parts being in their inactive or retracted positions as seen inFIGS. 1A and 18. Running string S will usually be a conventional wireline string including conventional jars (not shown) by which jarringimpacts can be directed through the running string to the toolssuspended thereon. The thus suspended drilling unit will be loweredthrough the bore of casing P until the anchor sub-assembly is landed onpins 13 in the landing shoe. Thereupon, downward jarring blows appliedthrough the running string will serve to break the inner portions ofshear pins 50 which secure setting sleeve 42 to shear sleeve 48, thelatter being held stationary by its seating on the upper end of cage 26.Thereupon, the downward jarring will drive setting sleeve 42 downwardlysufficiently to move enlargement 44 behind dogs 30 projecting themoutwardly into recess 14 (FIG. 2A) and thereby anchoring the unit to thelanding shoe.

With the drilling unit thus anchored to the lower end of the casing,upward pull, accompanied by upward jarring, if necessary, will beapplied through the running string and running collar 56 to shear sleeve48 to thereby apply sufficient upward force to break the portions ofshear pins 50 connecting shear sleeve 48 to collar 38 (FIG. 3). Thisreleases the running string from the drilling unit allowing the runningstring to be withdrawn from the casing and leaving the drilling unitanchored to the lower end of casing.

Fluid, such as water or drilling mud will now be pumped down the casingand through the several connecting bores in the drilling unit. The fluidwill pass through passageway 61 actuating rotor 60 and shaft 62 torotate the bit section. The pressure fluid discharging from passageway61 will flow into bore 71 of the bit section applying pressure to piston77 by reason of the flow restriction formed by the reduced diameter flowpassages defined by bore 79 of the plunger and the still smallerdiameter jets and wash ports through which the fluid finally dischargesfrom the bit section. The fluid pressure thus applied to the plungerwill supplement the force of spring 82 sufficiently to break shear pins91, thereby releasing the underreamers for movement to their extendedpositions and being held extended by the combination of the forcesexerted by spring 82 and the fluid pressure while the bit section isbeing rotated by the power drive unit. As the drilling progresses,sections of casing will be added to the upper end of the casing stringsimilarly to the procedures employed in conventional rotary drillingusing ordinary drill pipe.

When necessary to withdraw the drilling unit from the casing in order torepair or replace the pilot bit, underreamers or any other part of theunit, then, as seen in FIG. 4, a fishing tool, designated generally bythe letter T, of any generally conventional form, the details of whichdo not form a part of this invention, will be run into the casing boreon a wire line or tubing string, as desired, and will be latched beneatha downwardly facing shoulder 93 in the bore of setting sleeve 42. Onapplication of upward pull to the fishing string, the setting sleevewill be drawn upwardly moving enlargement 44 above dogs 30, to theposition shown in FIG. 1A, thereby releasing the dogs for retractionfrom recess 14. Continued upward pull will then draw the underreamersinside landing shoe 10, the flared lower end 12 of the latter acting onthe underreamer arms to collapse the underreamers against the oppositionof spring 82 in response to the upward pull being applied to thedrilling unit and thus allow the entire drilling unit to be withdrawnthrough the casing bore to the surface.

When drilling is to be resumed, the drilling unit, with the parts in theoriginal retracted positions, will be returned through the bore of thecasing to its lodgrnent in shoe 10, reanchored therein and fluidpressure reapplied to rotate the bit section and thereby resume thedrilling operation.

From the foregoing it will be evident that a drilling system is providedin which the casing itself, which is ordinarily required to line thepreviously drilled bore hole, will be continuously, non-rotatively fedinto the bore hole as the drilling proceeds, thereby obviating all ofthe additional operations conventionally required in rotary drilling andfor easing the well. The hazards accompanying the conventional drillingand casing operations, including those arising from round trips of thedrill string, will be obviated, drilling operations greatly facilitated,and time of operation substantially reduced.

While the illustrative embodiment discloses the use of a fluidpressure-type power drive, it will be evident that drive unit B may be afluid operated turbine, or an electric motor. Various othermodifications and variations may be made in the details of theillustrative embodiment within the scope of the appended claims butwithout departing from the spirit of this invention.

What I claim and desire to secure by Letters Patent is:

1. In the rotary drilling of wells, the combination of:

a. a string of well casing;

b. a drilling assembly constructed and arranged to be bodily insertedand removed through the bore of said well casing; said assemblycomprising:

i. anchor means for releasably securing said drilling assembly to thelower end portion of said casing and against rotation relative thereto,including;

i,. a landing shoe carried by the lower end of the casing and having anannular recess circumferentially about the inner wall thereof;

i a tubular cage slidably receivable in said shoe;

i anchor dogs mounted in the wall of said cage for radial movement intoand out of said recess;

i a setting sleeve slidably mounted in the bore of said cage formovement between position actuating and releasing said anchor dogs; and

i means initially securing said setting sleeve in the dog-releasingposition and releasable for movement to the dog-actuating position byapplication of downward jarring force to said sleeve;

ii. a rotary drive member secured to said anchor means;

and

iii. a pilot bit and underreamer assembly secured to said drive memberfor rotation thereby.

2. The combination of claim 1 wherein said anchor means includes:

a. landing pins projecting inwardly from the inner wall of said shoebelow said recess; and

b. landing slots in the exterior of said cage positioned to receive saidlanding pins to limit relative downward movement of said cage and tohold said cage against rotation relative to said shoe.

3. The combination of claim 1 wherein said rotary drive member is fluidpressure-operated.

4. The combination of claim 1 wherein said pilot bit and underreamerassembly comprises:

a. a tubular body connectible to the lower end of said drive member;

b. a pilot bit carried by the lower end of said body;

c. a plurality of angularly spaced underreamers pivotally mounted to thebody above the pilot bit for radial extension and retraction;

d. actuating means mounted in said body normally biasing saidunderreamers to extended position; and

e. releasable means initially securing said underreamers in retractedpositions.

5. The combination of claim 4 wherein:

a. said rotary drive member is operated by fluid pressure appliedthrough said casing; and

b. release of said releasable means is effected by said fluid pressure.

6. The combination of claim 4 wherein said actuating means includes:

a. plun er means slidably mounted in said body; b. cran means operablyconnecting said plunger means to said underreamers; and c. coil springmeans mounted in downwardly biasing relation to said plunger means.

1. In the rotary drilling of wells, the combination of: a. a string ofwell casing; b. a drilling assembly constructed and arranged to bebodily inserted and removed through the bore of said well casing; saidassembly comprising: i. anchor means for releasably securing saiddrilling assembly to the lower end portion of said casing and againstrotation relative thereto, including; i1. a landing shoe carried by thelower end of the casing and having an annular recess circumferentiallyabout the inner wall thereof; i2. a tubular cage slidably receivable insaId shoe; i3. anchor dogs mounted in the wall of said cage for radialmovement into and out of said recess; i4. a setting sleeve slidablymounted in the bore of said cage for movement between position actuatingand releasing said anchor dogs; and i5. means initially securing saidsetting sleeve in the dogreleasing position and releasable for movementto the dogactuating position by application of downward jarring force tosaid sleeve; ii. a rotary drive member secured to said anchor means; andiii. a pilot bit and underreamer assembly secured to said drive memberfor rotation thereby.
 2. The combination of claim 1 wherein said anchormeans includes: a. landing pins projecting inwardly from the inner wallof said shoe below said recess; and b. landing slots in the exterior ofsaid cage positioned to receive said landing pins to limit relativedownward movement of said cage and to hold said cage against rotationrelative to said shoe.
 3. The combination of claim 1 wherein said rotarydrive member is fluid pressure-operated.
 4. The combination of claim 1wherein said pilot bit and underreamer assembly comprises: a. a tubularbody connectible to the lower end of said drive member; b. a pilot bitcarried by the lower end of said body; c. a plurality of angularlyspaced underreamers pivotally mounted to the body above the pilot bitfor radial extension and retraction; d. actuating means mounted in saidbody normally biasing said underreamers to extended position; and e.releasable means initially securing said underreamers in retractedpositions.
 5. The combination of claim 4 wherein: a. said rotary drivemember is operated by fluid pressure applied through said casing; and b.release of said releasable means is effected by said fluid pressure. 6.The combination of claim 4 wherein said actuating means includes: a.plunger means slidably mounted in said body; b. crank means operablyconnecting said plunger means to said underreamers; and c. coil springmeans mounted in downwardly biasing relation to said plunger means.